1. Field of the Invention
The present invention relates to a method of controlling combustion of a diesel engine, and more particularly, to a method of controlling combustion of a diesel engine where a fuel injection timing is controlled not by directly measuring a combustion pressure but by estimating a maximum pressure of a combustion chamber through vibrations.
2. Description of Related Art
In the related art, pressure in a cylinder of a diesel engine has been directly measured for controlling combustion of the diesel engine so that the measured pressure of the cylinder has been used in controlling combustion of the diesel engine.
For example, according to a combustion control method according to the related art, a pressure sensor is directly mounted within a cylinder and an engine RPM sensor, an engine load sensor, and a crack angle sensor are mounted to the engine, and an engine is controlled by using a cylinder pressure, an engine RPM, an engine load, and a crank angle measured by the sensors as shown in FIG. 1.
That is, as shown in FIG. 2, if an operation of an engine is started (S210), a combustion pressure of a combustion chamber is measured depending on a crank angle (S220), a crank angle corresponding to an MFB (mass fraction burning) 50 is measured by using the measured pressure of the cylinder (S230), a point corresponding to the MFB 50 is measured as the engine is operated, a correction value is calculated by comparing a target MFB 50 and the calculated MFB 50 (S240), and main injection timing is corrected and controlled by using the calculated correction value (S250).
However, according to the method of controlling combustion of a diesel engine in the related art, it is required to directly mount a pressure sensor within a cylinder for control, and the pressure sensor is expensive and a factor necessary for control is supposed to be obtained by measuring pressure based on a crank angle.
Further, since expensive pressure sensors for measuring combustion pressure-installed in cylinders and wires for connecting the pressure sensors is required, manufacturing costs of a vehicle increase.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.